velocity model for testing travel_time_new.m
remark: 1:Corad discon.; 2: Moho discon.vp/vs=1.73
no   top-depth  P(km/s)  S(km/s) remark
1     0        6.0           3.47    0
2     16       6.0           3.47    0
3     20       6.0           3.76    1
4     30       6.0          3.76    0
5     40       7.97           4.61    2
6     100      7.97           4.61    0